1. Field of the Invention
The present invention relates generally to power supplies/battery packs and more particularly to a compressed air powered power supply/self-charging battery pack for use in a railroad End of Train (EOT) unit or other electrical products where suitable compressed air is available.
2. Description of the Related Art
Within the railroad industry, End-of-Train (EOT) units coupled to the last car of a train are extensively used to monitor operating characteristics of the train. Information is typically transmitted to equipment, usually located in the locomotive, where it is processed and used for operation of the train.
Conventional EOT devices are currently powered by replaceable rechargeable battery cells, such as for example Nickel/Cadmium or sealed lead acid batteries. FIG. 1 illustrates in block diagram form a railroad train 10 with an EOT unit 12. Train 10 includes a locomotive unit 14. An air brake pipe 26 extends through cars 18 to the EOT unit 12. EOT unit 12 monitors the pressure in the air brake pipe 26 via transducer 28 and transmits this information, as well as other information, via transmitter 24 to locomotive unit 14. Battery pack 20 provides power for the EOT unit 12.
There are problems, however, with the use of battery cells, such as battery pack 20, in EOT units. Typically, when the battery cells become discharged, the EOT unit is rendered inoperable until the battery cells are replaced by charged cells, or are recharged by connection to an external power source. In some instances, the battery cells may have to be replaced or recharged in remote places, requiring the railroad to have batteries or battery chargers located throughout the railroad. The resulting down time of the EOT unit results in increased cost of operation for the railroad.
Thus, there exists a need for a power supply for use in an EOT unit that requires minimal maintenance and can provide continuous operation, thereby reducing EOT down time and increasing efficiency of the railroad.